Downhole Tool With Counting Mechanism

ABSTRACT

An object counting mechanism for a downhole tool which includes a tool housing having a central passage and a seat configured to selectively catch an object passing through the central passage. An activating mechanism is configured to move the seat from a first state allowing the object to pass through the seat into a second state for catching the object on the seat. A rotating sleeve causes the activating mechanism to move the seat into the second state after a given degree of rotation of the rotating sleeve. At least one contact surface is spaced apart from the seat and positioned to engage the object passing through the central passage, thereby effecting a limited rotation of the rotating sleeve at each passage of an object.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit under 35 USC §119(e) of U.S. provisional application Ser. No. 62/031,423 filed Jul. 31, 2014, which is incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

The present invention relates to downhole tools typically used in oil and gas wells. In many instances, such downhole tools are activated by way of a ball drop system. Nonlimiting examples of such downhole tools may include a sleeve which is shifted in a sliding sleeve valve. A well with a ball drop system typically includes a string of piping or tubing with a series of tools positioned along the string. A “ball seat” is associated with many or all of the tools and the ball seat is intended to “catch” a ball, dart, plug, or other suitably shaped object (hereinafter referred to collectively as a “ball” or “object”) which is dropped or pumped down the string until the ball engages a seat. Applying pressure to the fluid above the seated ball provides the mechanical force necessary to activate the tool.

One prior art ball drop system includes multiple ball seats where the respective diameters of the seats become progressively smaller with the depth of the string. This permits a plurality of balls having a progressively increasing diameter, to be dropped (or pumped), smallest to largest diameter, down the well to operate the various tools in the string, starting from the toe of the well and moving up. However, it is typically undesirable to constrict the internal diameter of the string any more than necessary. Therefore, it would be advantageous to have a ball drop system which either utilizes many seats of the same (largest possible) diameter, or at least fewer seats of decreasing diameter. To accomplish this, the ball drop system should preferably have a mechanism to allow a certain number of balls to pass a particular seat before that seat catches the next ball.

SUMMARY OF SELECTED EMBODIMENTS OF THE INVENTION

One embodiment of the invention is a sleeve valve having a tubular valve housing having flow ports and a central passage and a closing sleeve assembly operatively attached to a catch seat assembly. A rotating sleeve acts to initially maintain the catch seat assembly in a pass-through position and releases the catch seat assembly into a catch position after a given degree of rotation of the rotating sleeve. A rocker arm is spaced apart from the catch seat assembly, with the rocker arm positioned to engage an object passing through the central passage and cause a limited rotation of the rotating sleeve.

Another embodiment of the invention is an object counting mechanism for a downhole tool which includes a tool housing having a central passage and a seat configured to selectively catch an object passing through the central passage. An activating mechanism is configured to move the seat from a first state allowing the object to pass through the seat into a second state for catching the object on the seat. A rotating sleeve causes the activating mechanism to move the seat into the second state after a given degree of rotation of the rotating sleeve. At least one contact surface is spaced apart from the seat and positioned to engage the object passing through the central passage, thereby effecting a limited rotation of the rotating sleeve at each passage of an object.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a cross-sectional view of one embodiment of the present invention.

FIG. 2 illustrates one embodiment of a ported housing section.

FIG. 3 illustrates one embodiment of a counting sleeve.

FIG. 4 illustrates one embodiment of a rotating sleeve.

FIG. 5 illustrates one embodiment of a counting lever.

FIG. 6 illustrates one embodiment of a constricting finger sub.

FIGS. 7A and 7B illustrate an assembled rotating sleeve and constricting finger sub.

FIGS. 8A and 8B illustrate the operation of the counting lever.

FIGS. 9A and 9B are detailed sections of FIGS. 8A and 8B.

FIGS. 10A and 10B illustrate the operation of the constricting finger sub.

FIGS. 11A and 11B are detailed sections of FIGS. 10A and 10B.

FIGS. 12A and 12B illustrate a mechanism for allowing rotating sleeve rotation in only one direction.

FIG. 13 illustrates a cross-sectional view of a second embodiment of the present invention.

FIGS. 14A and 14B illustrate cross-sectional views of an alternative seat base.

FIGS. 15A to 15D illustrate an alternative counting lever.

FIGS. 16A and 16B illustrate an alternative mechanism for effecting one-way sleeve rotation.

DETAILED DESCRIPTION OF SELECTED EMBODIMENTS

FIG. 1 illustrates one embodiment of a tool according to the present invention, a sliding sleeve valve with a ball or “object” counting mechanism. It will be understood that FIG. 1 shows the tool broken into two sections to better illustrate the components, but the tool is in fact a continuous structure (see for example, FIG. 8A). This valve or tool 1 most generally comprises a tubular valve housing 2, which is the outermost tubular component of the tool, with flow ports 7 and a central passage 6. A closing sleeve assembly 10 (sometimes referred to as a “shifting sleeve” assembly) is positioned within housing 2 and is operatively connected to a catch seat assembly 28. A rotating sleeve 24 is positioned within the closing sleeve assembly 10 and acts to initially maintain the catch seat assembly in a pass-through position and then release the catch seat assembly into a catch position after a given degree of rotation of the rotating sleeve. A counting lever (or “rocker arm”) 26 is positioned to be engaged by the ball passing through the central passage and allows a limited rotation of the rotating sleeve with each operation of the counting lever.

More specifically describing the tool components, the “upper” (leftmost) end of the tool housing 2 seen in FIG. 1 includes the ported housing section 3 having the internally threaded connector 8 and a series of flow ports 7 allowing a fluid path between the exterior of the housing and central passage 6. While FIG. 1 shows flow ports 7 as simple apertures, alternate embodiments could have flow ports fitted with burst discs or similar devices designed to fail at a predetermined pressure. Ported housing section 3 threads into main housing section 4 which extends the length of the tool and terminates in externally threaded connector 9. It will be understood that externally threaded connector 9 and internally threaded connector 8 allow the tool to be connected to other tools, pipe subs, or otherwise inserted within the tubular string. The closing sleeve assembly 10 encompasses a series of components capable of moving axially (i.e., in a direction along the length of the tool) as a single assembly within housing 2, namely sleeve end 11, spring housing 13, and counting drum or counting sleeve 22. It may be seen that sleeve end 11 acts to block flow ports 7 (sealed by o-rings 12) when the closing sleeve assembly 10 is in its port-blocking or closed position. As seen in more detail in FIG. 2, sleeve end 11 will have an anti-rotation slot 71 which is engaged by anti-rotation pin 70 carried by ported housing section 3 and allows axial movement or translation, but not rotation, of closing sleeve assembly 10 relative to housing 2. FIG. 2 also shows shear screw or shear pin apertures 72 and 73 formed in ported housing section 3 and sleeve end 11, respectively. It will be understood that when sleeve end 11 is in the closed position, shear screws will engage apertures 72 and 73 in order to hold the sleeve in the closed position until sufficient force is applied to fail the shear screws. FIG. 2 also shows a sliding ratchet mechanism 75 which allows sleeve end 11 to move in the open (ports unblocked) direction, but resists movement in the closed direction in order to prevent unintentional closing of the valve once opened. The ratchet mechanism is best seen in Detail I of FIG. 2 and includes the ratchet teeth 76 on sleeve end 11, ratchet ring 77 positioned in recess 80, and ratchet teeth 79 formed on ratchet ring 77 (which in one preferred embodiment is snap ring type of structure, e.g., a ring with a broken segment). It can be seen how movement of sleeve end 11 away from ported housing section 3 tends to spread ratchet ring 77 up into recess 80 and out of engagement with ratchet teeth 76. However, movement of sleeve end 11 toward ported housing section 3 moves inclined surface 78 on ratchet ring 77 into a corresponding inclined surface in recess 80, thereby forcing the ratchet teeth 76 and 79 into engagement and thereby preventing relative movement of ported housing section 3 and sleeve end 11 in this direction.

FIG. 1 illustrates how spring housing 13 connects sleeve end 11 with counting sleeve 22 and covers torsion spring 14. As best seen in the cut-away view of FIG. 3, counting sleeve 22 generally has a smooth outer surface for sliding within housing 2 and a number of internal shapes and profiles for interacting with other tool components. Counting sleeve 22 has internal threads 49 for engaging spring housing 13 on one end and seat base 30 on the opposite end (as seen in FIG. 1). Counting sleeve 22 further has at least one set of indexing teeth 50 formed around its inner circumference for engagement by the counting lever 26 (described below). In the particular embodiment of FIG. 3, counting sleeve 22 has two sets of indexing teeth, 50A and 50B. As explained in more detail below, there is a series of apertures or windows 52 to allow observation of a rotating sleeve inside counting sleeve 22 and a spring shoulder 55. A series of ball races 54 will be formed along the internal circumference of counting sleeve 22, with four ball races 54 seen in the FIG. 3 embodiment. Naturally, more or fewer races could be employed in other embodiments. Along each ball race, a ball release aperture 53 is formed through counting sleeve 22. In the FIG. 3, there are four ball release apertures (corresponding to the four races) spaced 90 degrees apart around the counting sleeve's circumference in order to evenly distribute the load carried by the ball within the races. It will be understood that the ball release apertures are axially spaced apart in order for each aperture to communicate with its representative ball race.

Again viewing FIG. 1, positioned to the interior of counting sleeve 22 is the rotating sleeve 24 (sometimes also referred to as “counting body” 24). The individual features of this embodiment of rotating sleeve 24 are best seen in FIG. 4. Rotating sleeve 24 includes a counting lever slot 85 to accommodate the counting lever 26 (seen in FIG. 1). In the illustrated embodiment, the pivot aperture 86 accepts a pin on which counting lever 26 will rotate. FIG. 5 shows one example of a counting lever 26 in greater detail. This is a double-ended counting lever having first end 60 and second end 61. Each end includes counting tooth 63 having a vertical surface 64 and inclined or arcuate surface 65. A pin will be inserted through pin aperture 62 and pivot aperture 86 to maintain counting lever 26 in the counting lever slot 85 of rotating sleeve 24. It can be envisioned how counting lever 26 may act as a rocker arm by pivoting slightly up and down on the pivot pin. FIG. 4 also shows how rotating sleeve 24 has at one end clutch teeth 17 which will form part of a clutch assembly (described in reference to FIGS. 7A and 7B further below).

A further component of closing sleeve assembly 10 is constricting finger sub (or “key sub”) 35. FIG. 1 shows how constricting finger sub 35 is generally positioned between rotating sleeve 24 and counting sleeve 22. FIG. 6 individually illustrates constricting finger sub 35 and shows how it generally includes cylindrical sub base 36 having a series of individual, flexible finger projections 57 extending therefrom. The finger projections have the tapered end surface 58 intended to engage the constricting shoulder 31 of seat base 30 (see FIG. 1). Sub base 36 further includes a series of ball pockets 40, spaced along its outer circumference, with the FIG. 6 embodiment having four ball pockets 40 spaced at 90 degree intervals. As explained below, the ball pockets 40 will correspond to the ball races 54 on counting sleeve 22. Additionally, a spring shoulder 42 extends along an internal circumference of sub base 36 and at least one axial or longitudinal slot 41 extends partially down sub base 36. The longitudinal slot 41 will be engaged by key 88 on rotating sleeve 24 (see FIG. 4) in order to allow relative axial or longitudinal movement between constricting finger sub 35 and rotating sleeve 24, but prevent relative rotation between these components. The illustrated embodiment of constricting figure sub 35 also includes an external band of teeth 43 which forms part of a one-way rotation mechanism and is explained further below in conjunction with FIGS. 12A and 12B.

FIGS. 7A and 7B show a partial assembly of rotating sleeve 24 with counting lever 26 and constricting finger sub 35 engaged therewith. The clutch assembly 15 is formed torsion spring clutch section 16 whose teeth engage corresponding teeth on the counting sleeve clutch section 17. It will be understood that when torsion spring 14 imparts torque to the spring clutch section 16, the torque is transferred to counting sleeve clutch section 17 and thus to rotating sleeve 24 as a whole.

The operation of the illustrated embodiment of valve/counting mechanism 1 can be visualized with reference to FIGS. 8 to 11. FIG. 8A suggests a ball 200 moving through central passage 6 just prior to engaging first end 60 of counting lever 26 while FIG. 8B illustrates ball 200 having moved past first end 60 and just prior to engaging second end 61 of counting lever 26. FIG. 9A and its cross-sections X-X and Y-Y best show how counting lever 26 engages the internal teeth 50A and 50B on counting sleeve 22. In FIG. 9A, the ball 200 has yet to engage first end 60 of lever arm 26. As seen in cross-section X-X, the first lever arm end 60 (and its tooth 63) is in a lower position out of engagement with the teeth 50A of counting sleeve 22. On the other hand, second lever arm end 61 seen in cross-section Y-Y has its tooth 63 engaging counting sleeve teeth 50B. As suggested in FIG. 9B, as ball 200 passes first lever arm end 60 and approaches second lever arm end 61, this position of lever arm 26 will be reversed. Thus, for each passing of a ball 200, the tooth 63 on each lever arm end 60 and 61 will engage and disengage its respective set of counting sleeve teeth 50A and 50B. It will be understood from the earlier description of torsion spring 14 (e.g., see FIG. 7B) that torsion spring 14 is applying torque to rotating sleeve 24, which is of course carrying counting lever 26. In this manner, torsion spring 14 constantly applies torque to rotating sleeve 24 and helps ensure that each movement of counting lever 26 effects a limited degree of rotation by rotating sleeve 24 relative to counting sleeve 22 when the teeth 63 move into and out of engagement with counting sleeve teeth 50A and 50B. In the illustrated embodiment, there are approximately sixty teeth in each set of teeth 50A and 50B, with each tooth spaced about 6° apart. It will be understood that each tooth 50A is about 3° offset from its corresponding tooth 50B. Therefore, in this example, about sixty balls will pass counting lever 26 to cause a full 360° rotation of rotating sleeve 24 relative to counting sleeve 22.

The function of sleeve 24's rotation can be understood in reference to the triggering balls 47 (see FIG. 1) which are riding in the ball pockets 40 of constricting finger sub 35 (best seen in FIG. 6) and ball races 54 of counting sleeve 22 (best seen in FIG. 3). The activation spring 45, which is positioned between the spring shoulder 55 on counting sleeve 22 and the spring shoulder 42 on constricting finger sub 35, acts to bias constricting finger sub 35 toward seat base 30. However, as long as triggering balls 47 are in the ball races 54 and engaging ball pockets 40, constricting finger sub 35 cannot move toward seat base 30. The sequence of actions which result in the release of constricting finger sub 35 is best seen in FIGS. 11A and 11B. In FIG. 11A, rotating sleeve 24 and constricting finger sub 35 (and thus triggering balls 47 carried in ball pockets 40) are rotating a discrete angular distance within counting sleeve 22 with the passing of each successive ball 200 past counting lever 26. The cross-section Z-Z best illustrates how triggering balls 47 are riding in races 54 and ball pockets 40 and have not yet reached ball release apertures 53 in counting sleeve 22. In this position, triggering balls 47 hold constricting finger sub 35 in the axial position seen in FIG. 11A. Because constricting finger sub 35 is prevented from moving toward seat base 30, the balls 200 pass through the opening in seat base 30 at this stage of the tool's operation.

However, with continued rotation of rotating sleeve 24 and constricting finger sub 35, triggering balls 47 eventually become aligned with ball release apertures 53 as seen in FIG. 11B and cross-section W-W. At this point, the force on constricting finger sub 35 from activation spring 45 will urge triggering balls 47 into ball release apertures 53. Now triggering balls 47 no longer block constricting finger sub 35 from moving forward relative to rotating sleeve 24. As activation spring 45 pushes constricting finger sub 35 forward, the tapered end surface 58 of finger projections 57 will be forced to constrict or collapse more closely together as they engage the inclined constricting shoulder 31 of seat base 30. As suggested by FIG. 11B, the inner surface of finger projections 57 now form a sufficiently reduced diameter that the next ball 200 will be “caught” and held in place. At this point, the application of fluid pressure in the central passage 6 above ball 200 will provide sufficient force to move the entire closing sleeve assembly 10 downward (including shearing shear screws in apertures 72 and 73 in FIG. 2) as seen in FIG. 10B. Thus, the sleeve end 11 uncovers flow ports 7 and fluid communication is established between central passage 6 and the exterior of tool 1 (i.e., the valve is in the open position). In certain embodiments, the finger projections 57 and the seat base 30 may have a rubber-like coating to increase the sealing effect of the ball-fingers-seat interaction.

It will be apparent from the above description that the number of balls 200 passing the counting lever 26 before constricting finger sub 35 is released depends on how far the ball pockets 40 are initially angularly offset from the ball release apertures 53. In one embodiment, numbers marked around the circumference of constricting finger sub base 36 will be visible through view windows 52 in counting sleeve 22. These numbers will indicate how far the ball pockets 40 are angularly offset from ball release apertures 53 and thus, the number of balls 200 needing to pass the counting lever 26 before constricting finger sub 35 is released.

As suggested above, a tubular string will typically have many tools 1 incorporated along its length and it will be desired to actuate the tools in sequence from the lowermost tool first to the uppermost tool last. Thus, if a string has ten tools, each having the above described counting mechanism, the lowermost tool could be activated by the passing of the first ball 200, while the uppermost tool would be activated by the passing of the tenth ball 200.

FIGS. 12A and 12B illustrate an alternate embodiment of counting sleeve 22 which incorporates a ratchet mechanism between the rotating sleeve and the counting sleeve, thereby functioning to allow movement in the rotational direction driven by the rocker arm, but resisting rotational movement in the opposite direction. FIG. 12B is a cross-section of counting sleeve 22 taken at the location of ratchet mechanism 89, but the Details I to III best show the individual components of ratchet mechanism 89. This example of ratchet mechanism 89 is formed by a series of ratchet blocks 90 positioned in slots or pockets 93 formed in the sidewall 92 of counting sleeve 22. The pockets 93 are formed through counting sleeve sidewall 92, but a circular spring 95 is positioned around the section of counting sleeve 22 having pockets 93 and acts to contain the ratchet blocks 90. It can be seen that the ratchet blocks 90 are positioned over the band of ratchet teeth 43 formed on constricting finger sub 35 (see FIG. 6). Moreover, the ratchet blocks 90 each have a tooth member 94 with a sloped surface for engaging ratchet teeth 43. In the Details I to III, it can be envisioned how ratchet blocks 90 allow movement in the clockwise direction, but resist movement in the counter-clockwise direction. When torque is applied to constricting finger sub 35 in the clockwise direction, the sloped surface on tooth members 94 can ride up the corresponding sloped surface on ratchet teeth 43. The ratchet blocks 90 are able to deflect away from ratchet teeth 43 by temporarily expanding circular spring 95, thereby allowing each ratchet tooth 43 to displace and rotate under the ratchet block 90. When the sloped surfaces of tooth members 94 and ratchet teeth 43 completely pass one another, circular spring 95 pulls ratchet block 90 downward such that the vertical walls of tooth member 94 and ratchet teeth 43 are engaged as suggested in Detail III. It can be seen that if a counter-clockwise torque is applied to constricting finger sub 35, this force will be resisted by the engaged vertical surfaces of the teeth. However, further clockwise torque will again start relative movement along the sloped surfaces of the teeth and ultimately result in passage of another tooth 43 relative to each tooth member 94. Obviously, the direction of allowed rotation and blocked rotation may be easily reversed by changing the slope direction of the teeth. Moreover, FIGS. 12A and 12B illustrated merely one example of a ratchet mechanism and persons skilled in the art will readily recognize other ratchet mechanisms which could be employed as alternatives.

Another embodiment of the tool with a counting mechanism is illustrated in FIGS. 13 to 16. FIG. 13 shows a tool 100 which is largely similar to the tool 1 described in FIG. 1. FIGS. 14 to 16 focus on the primary features where tool 100 varies from tool 1. In FIG. 13, the tool 100 is generally shown as including upper ported housing section 103 threated to main outer housing section 104, which terminates with bottom connector sub 109. The primary variations from tool 1 are suggested by unidirectional rotation lock 190, counting lever 126, and seat base 130. Except as explained below, it may be presumed that the embodiment of FIGS. 13 to 16 operates in substantially the same manner as the embodiment of FIGS. 1 to 12.

FIGS. 14A and 14B show in more detail how the seat base 130 includes a series of dogs 135. Although the cross-section of FIGS. 14A and 14B only show two dogs 135, it can be seen in FIG. 14C that this embodiment has a series of dogs 135 (six in FIG. 14C) spaced circumferentially around seat base 130. Viewing FIG. 14B, the dogs 135 will be pivotally secured by pins 137 in notches 134 formed on the end of seat base 130. As suggested in FIG. 14A, balls moving in a “downward” direction toward seat base 130 will be able to rotate dogs 135 out of the central passage and continue on the ball's path down the central passage. However, if fluid flow is (intentionally or unintentionally) reversed in the central passage, the dogs 135 rotate rearward against the rear walls 136 of notches 134, thereby blocking any “upward” movement of balls which are below seat base 130. In many embodiments, dogs 135 will not require any mechanism biasing them in the rearward position and will rely on a tendency of an “upward” moving ball to engage the edges of the dogs in order to move them to the rearward or closed position. However, there may also be embodiments where springs or other biasing mechanisms act to bias the dogs in the rearward or closed position, while allowing balls to push past the dogs when moving in the “downward” direction.

FIGS. 15A to 15D illustrate this embodiment's modifications to counting lever 126. First, a rod and roller mechanism is positioned in slots 160 on each side of counting lever 126 and provide a measure of resistance to the rocking motion of counting lever 126. It can be envisioned from FIGS. 15A and 15B how the rods 161 extend through the rollers 162. The slots 160 are formed such that rollers 162 may be forced into deeper crevasses in slots 160, but the rods 161 (in a shallow section of slots 160) will constantly bias rollers 162 outward towards the sidewalls of counting lever slot 85 (see FIG. 4) in the counting body rotating sleeve 24. In this manner, the significant force of a ball moving past counting lever 126 will cause it to rock as described above, but lesser forces are less likely to cause inadvertent rocking. Second, FIGS. 15A, 15C, and 15D also show a series of screws positioned in counting lever 126. Shear screw 165 enters counting lever 126 on its bottom surface and acts to initially prevent counting lever 126 from traveling upward in the counting lever slot 185. As seen in FIG. 15C, the edge of the head of shear screw 165 will engage the inner surface of counting body rotating sleeve 124 and resist upward movement of counting lever 126. Upon application of sufficient force (e.g., a ball being forced through the tool's central passage by fluid pressure), this edge of shear screw 165 will fail and allow counting lever 126 to rock though its full range of motion. The screws 164A and 165B extend into counting lever 126 from its top surface and as suggested in FIG. 15D, will limit downward movement of counting lever 126 by the edge of the screw heads engaging the outer surface of counting body rotating sleeve 124. Screws 164A and 164B will allow counting lever 126 to rock in its normal operational range of motion. However, if counting lever pivot pin 163 were to fail, the screws 164A and 164B would prevent the counting lever 126 from falling into the central passage and becoming an obstruction.

FIGS. 16A and 16B illustrate an unidirectional rotation lock which may operate as a substitute for the ratcheting mechanism seen in FIG. 12. FIG. 16B illustrates how slots 193 are formed on the outer surface of clutch section 116 attached to the torsion spring (see clutch section 16 in FIG. 7A for the analogous structure of the previous embodiment). Positioned within the slots 193 are balls 191 which are biased outwardly by springs 192 such that balls 191 tend to engage the inner surface of spring sleeve 113. Thus, it may be seen how counter-clockwise rotation of clutch section 116 (relative to the view of FIG. 16B) will tend to wedge ball 191 in the increasingly narrow portion of slot 193, thereby preventing relative rotation between clutch section 116 and spring sleeve 113. On the other hand, clockwise rotation of clutch section 116 will urge ball 191 into the wider portion of slot 193 where ball 191 will not wedge against spring sleeve 113, thereby not impeding clockwise rotation.

Although the above described figures disclose one example of the present invention, all obvious variations and modifications of the illustrated embodiments are included as part of the present invention. As one example, rather than one counting lever 26, there could be multiple, circumferentially spaced, counting levers (e.g., two or three counting levers). As a further example, counting lever 26 need not have a rocker arm configuration. Rather, the lever arm could be a single radially moving “button” or “contact surface” which moves in and out of engagement with a single set of counting sleeve teeth 50 with the passing of the ball 200. Alternatively, the rocker arm could be replaced with two, independently actuable, “buttons” for engaging two sets of teeth as described above. In certain embodiments, it may be desirable to form a harden coating (e.g., tungsten-carbide) onto the counting lever surface which engages the ball, thereby reducing the possibility of damage to the counting lever. Alternatively, the entire counting lever could be subject to a conventional or future developed hardening process.

As another example variation, the tool could have no torsion spring 14 and instead rely on the alternate engagement of rocker arm teeth having the vertical surface and inclined surface previously described. These teeth should rotate the rotating sleeve in only one direction even in the absence of the torsion spring.

Another variation would be to have each trigger ball 47 travel through two or more races before encountering a ball release aperture 53. Rather than the trigger ball entering a ball release aperture after a single rotation of the rotating sleeve, an aperture in the side wall of a first race would allow the trigger ball to move to a second, adjoining race. The ball would then complete a rotation in the second race before encountering the ball release aperture. This allows the rotating sleeve to make two complete rotations relative to the counting sleeve before the constricting finger sub is released. In essence, the number of balls passing the counting mechanism prior to activation of the tool is doubled by directing the trigger ball to travel through the second race. Obviously, this concept may be expanded to three races, four races, etc., for each ball if it is desired to require additional rotations of the rotating sleeve prior to release of the constricting finger sub.

Although the Figures show the counting mechanism operating a sliding sleeve type valve (i.e., sleeve 11 uncovering flow ports 7), the counting mechanism could operate other types of downhole tools. For example, the counting mechanism could activate a ball valve closing the central passage. Alternatively, the counting mechanism could be used to set a tool at a desired angular position in the wellbore. The above described variations and all other variations and modifications obvious from the embodiments described above are intended to come within the scope of the following claims. 

1. A sleeve valve comprising: a. a tubular valve housing having flow ports and a central passage; b. a closing sleeve assembly operatively attached to a catch seat assembly; c. a rotating sleeve acting to initially maintain the catch seat assembly in a pass-through position and releasing the catch seat assembly into a catch position after a given degree of rotation of the rotating sleeve; and d. a rocker arm spaced apart from the catch seat assembly, the rocker arm positioned to engage an object passing through the central passage and causing a limited rotation of the rotating sleeve.
 2. The sleeve valve of claim 1 wherein the rocker arm moves between a first and second position with the passing of the object and causes two discrete angular movements of the rotating sleeve.
 3. The sleeve valve of claim 1 wherein the rocker arm is positioned on the rotating sleeve.
 4. The sleeve valve of claim 3 wherein (i) the closing sleeve assembly includes a counting sleeve having an internal set of indexing teeth engaged by the rocker arm; and (ii) the rotating sleeve is positioned within the counting sleeve.
 5. The sleeve valve of claim 1 wherein the catch seat assembly includes (i) a seat base providing first diameter in the central passageway and (ii) a constricting finger sub which selectively engages the seat base to create a second smaller diameter in the central passageway.
 6. The sleeve valve of claim 5 wherein a ball riding in a race prevents the constricting finger sub from engaging the seat base.
 7. The sleeve valve of claim 6 wherein the race is formed on the inner surface of the counting sleeve.
 8. The sleeve valve of claim 6 wherein angular movement of the rotating sleeve allows the ball to move into a ball aperture and release the constricting finger sub to engage the seat base.
 9. The sleeve valve of claim 8 wherein the ball aperture is formed on the inner surface of the counting sleeve.
 10. The sleeve valve of claim 6 wherein the ball rides in a détente formed in a body portion of the constricting finger sub.
 11. The sleeve valve of claim 1 wherein a spring acts between the constricting finger sub and the rotating sleeve in order to release the catch seat assembly to the catch position.
 12. The sleeve valve of claim 1 wherein a torsion spring maintains a torque load on the rotating sleeve.
 13. The sleeve valve of claim 5, wherein the constricting finger sub is fixed against rotation relative to the rotating sleeve.
 14. The sleeve valve of claim 4 wherein a ratchet mechanism allows only one-way rotation of the rotating sleeve relative to the counting sleeve. 15-19. (canceled)
 20. An object counting mechanism for a downhole tool comprising: a. a tool housing having a central passage and a closure mechanism for closing the central passage; b. a shifting sleeve assembly positioned in the tool housing and activating the closure mechanism by axial movement in the tool housing; c. a rotating sleeve acting to initially hold the shifting sleeve assembly in a first position and releasing the shifting sleeve assembly to a second position after a given degree of rotation of the rotating sleeve; and d. a radially moving lever spaced apart from the closure mechanism and positioned to engage an object passing through the central passage and effecting a limited rotation of the rotating sleeve at each passage of an object.
 21. The object counting mechanism of claim 20 wherein the radially moving lever moves into and out of engagement with a set of indexing teeth.
 22. The object counting mechanism of claim 21 wherein the radially moving lever is a rocker arm having two opposing ends and each end moves alternatively into and out of engagement with a separate set of indexing teeth. 23-35. (canceled)
 36. An object counting mechanism for a downhole tool comprising: a. a tool housing having a central passage and a seat configured to selectively catch an object passing through the central passage; b. an activating mechanism configured to move the seat from a first state allowing the object to pass through the seat into a second state for catching the object on the seat; c. a rotating sleeve causing the activating mechanism to move the seat into the second state after a given degree of rotation of the rotating sleeve; and d. at least one contact surface spaced apart from the seat and positioned to engage the object passing through the central passage, thereby effecting a limited rotation of the rotating sleeve at each passage of an object.
 37. The object counting mechanism of claim 36, wherein the contact surface is formed on a counting lever.
 38. The object counting mechanism of claim 36, wherein activating mechanism is a shifting sleeve assembly positioned in the tool housing and moving the seat to the second state by axial movement of the shifting sleeve assembly. 